A motor vehicle includes a drive train which includes a prime mover or drive source, a gearbox, and a driving wheel. Different gear steps or ratios may be engaged in the gearbox in order to adapt a rotational speed of the prime mover to a rotational speed of the driving wheel. The gearbox includes multiple gear sets which may be differently configured and combined with the aid of shift elements. A control device controls the shift elements by way of an open-loop system and, in this way, determines which gear ratio is engaged, i.e., which step-down ratio (or step-up ratio) is present between an input side and an output side of the transmission, and determines with the aid of which gear sets in which configuration the step-down ratio is achieved. During a changeover from one gear ratio into another gear ratio, usually at least one shift element is disengaged and another shift element is engaged in order to achieve a changeover which is as smooth as possible.
In order to assist the gear step changeover, a torque introduced by a prime mover into the gearbox may be confined to a predetermined value with the aid of a demand. The range in which such a restriction is effective is limited, however, and so the open-loop control of the gearbox, for example, to a synchronization point of a gear step to be engaged with the aid of a specification of the introduced torque, may be difficult.
One problem addressed by the invention is that of providing an improved technique for the changeover of a gear step engaged in a gearbox.